Bandgap Reference Circuit Power Reduction via Segmented Amplifiers
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Solution Overview
Problem
Conventional bandgap reference circuits consume high power to maintain low noise levels, and are sensitive to process variations which affect the accuracy of the reference voltage, leading to errors in temperature-independent voltage generation.
Innovation Solution
A bandgap voltage reference circuit design that includes current paths mirroring each other, with an operational amplifier coupled to these paths and buffer stages to reduce noise amplification, using NMOS transistors to lower noise and power consumption while maintaining temperature independence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the operational amplifier consumes high power to maintain low noise levels, then noise performance is improved, but power consumption increases
Solution Approach 1:
The patent divides the operational amplifier into two separate operational amplifiers: one dedicated to noise-sensitive functions and another to offset compensation. This segmentation allows each amplifier to be optimized for its specific function, reducing the power consumption required for noise control while maintaining overall noise performance.
Solution Approach 2:
The patent introduces an intermediate buffer stage between the operational amplifier and the bandgap reference circuit. This buffer acts as an intermediary that isolates the operational amplifier from noise-sensitive nodes, allowing the amplifier to operate at lower power while maintaining noise performance through the buffer's impedance transformation properties.
2Measurement precision
If the input offset voltage of the operational amplifier is reduced to improve accuracy, then manufacturing precision requirements increase, but device complexity and cost increase
Solution Approach 1:
The patent implements a feedback mechanism where one operational amplifier specifically measures the offset voltage of the other operational amplifier and generates a compensating signal. This feedback loop dynamically corrects offset errors without requiring ultra-precise manufacturing, thereby maintaining accuracy while reducing manufacturing complexity.
Solution Approach 2:
The patent introduces an intermediate offset compensation circuit that acts as a mediator between the operational amplifier and the bandgap reference. This intermediary circuit measures and compensates for offset voltages, allowing the use of operational amplifiers with larger offset voltages while maintaining overall circuit accuracy.
3Stability of the object's composition
If process variations are reduced to improve reference voltage stability, then manufacturing complexity increases, but robustness decreases
Solution Approach 1:
The patent employs feedback mechanisms that continuously monitor and correct for process variations. By measuring deviations from the ideal reference voltage and applying corrective signals, the circuit maintains stability without requiring tight process control, thereby improving robustness to manufacturing variations.
Solution Approach 2:
The patent utilizes parameter changes in the operational amplifiers and compensating circuits to counteract process variations. By dynamically adjusting operating parameters such as bias currents and voltage levels, the circuit maintains reference voltage stability across varying process conditions without increasing manufacturing complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves reduced power consumption and noise contribution to the bandgap reference voltage, tolerating greater process variations without compromising power supply rejection ratio (PSRR) or temperature behavior, resulting in a more stable and efficient voltage reference.
Implementation Method 1
the first and second transistors are configured to generate a temperature dependent current in the first, second, and third current paths
Implementation Method 2
The operational amplifier 105 functions to equate the voltages V1 and V2 and generate a PTAT voltage across the resistor R
Implementation Method 3
By canceling the negative temperature dependence of the PN junctions in one group of transistors with the positive temperature dependence from a proportional-to-absolute-temperature (PTAT) circuit which includes the other group of transistors, a fixed DC voltage that does not change substantially with temperature is generated
Data Source
AI summary
A bandgap voltage reference circuit and methods for generating a bandgap reference voltage are disclosed. An operational amplifier receives first and second input voltages from a first and second current path, respectively. A buffer stage is coupled to an output of the operational amplifier and generates third and fourth voltages on the first and second path. A temperature dependent current is generated using the third and fourth voltages in combination with a first diode, second diode and a resistor. A third current path mirrors the temperature dependent current and a temperature independent voltage is generated for the bandgap reference voltage in the third current path using the temperature dependent current in combination with a second resistor and related diode.